To petition for probate or do an AP

[Arcinio Arauz]

I know this topic comes up often, but just wondering... I found a house, both owners passed away 10 years ago. House has been vacant since. Taxes became delinquent 4 years ago, owners had no children but does have other family members (sisters/brothers, nephews). At one point it seemed as if one sister cared for the house and payed the taxes but still kept it vacant. NO BANK/ MORTGAGE is involved!

So my question...in the event the sister wishes not to petition for probate (since house is still in descent's name) what else if anything can I do ? An AP (adverse possession) deal is one option yet because of lingering distant family members I am hesitant. Is there any other way ?  Can sister sign rights for me to petition or can I petition? Perhaps @Rick H. might know.